[IMP] http.py: Allow to use odoo if unmet dependencies on uninstalled module

Purpose
=======

If an external dependency is unmet on a module that is not installed, it's actually impossible to launch an odoo server and load the web client without getting a traceback.

This commit removes this constraint and allow to use odoo in that case. Obviously the install will crash if the external dependency is still unmet.

Close https://github.com/odoo/odoo/pull/17790
Coming from https://github.com/odoo/odoo/pull/14850

odoo/http.py

@@ -870,7 +870,6 @@ more details.
 #----------------------------------------------------------
 # Controller and route registration
 #----------------------------------------------------------
-addons_module = {}
 addons_manifest = {}
 controllers_per_module = collections.defaultdict(list)
 
@@ -1305,7 +1304,7 @@ class Root(object):
         statics = {}
         for addons_path in odoo.modules.module.ad_paths:
             for module in sorted(os.listdir(str(addons_path))):
-                if module not in addons_module:
+                if module not in addons_manifest:
                     mod_path = opj(addons_path, module)
                     manifest_path = module_manifest(mod_path)
                     path_static = opj(addons_path, module, 'static')
@@ -1316,11 +1315,6 @@ class Root(object):
                             continue
                         manifest['addons_path'] = addons_path
                         _logger.debug("Loading %s", module)
-                        if 'odoo.addons' in sys.modules:
-                            m = __import__('odoo.addons.' + module)
-                        else:
-                            m = None
-                        addons_module[module] = m
                         addons_manifest[module] = manifest
                         statics['/%s/static' % module] = path_static